Imagemagick convert resize then crop

Question

I have over 1000 images on different resolutions, (for example 1234x2122, 4400x5212 , etc) and I want to convert all of them to fixed 100x100 size, so.

first I need to resize the images keeping proportions, and get 100xA or Ax100, where A > 100 (it depends width and height of image, for some images width > height, and for some images height > width).
Crop this image to 100x100 from center

Is there a simple convert command, that I can use for all my images?

seems like what you want to do is similar to this http://www.imagemagick.org/discourse-server/viewtopic.php?t=18545 — phuclv, May 18 '17 at 16:03

score 72 · Accepted Answer · edited Feb 08 '17 at 15:05

72

You would use the area-fill (^) geometry modifier on the -resize operation to unify the down-scale. For cropping the center, -extent with -gravity Center will work.

convert input.jpg -resize 100x100^ \
                  -gravity Center  \
                  -extent 100x100  \
        output.jpg

Update

As Mark Setchell pointed out in the comments, the mogrify utility can be leveraged to batch convert items.

mogrify -path ./path/to/write/results/ \
        -resize 100x100^ \
        -gravity Center  \
        -extent 100x100  \
        ./path/to/source/files/*

Reminder: Mogrify will overwrite original file with resulting image(s), unless you set the -path parameter.

edited Feb 08 '17 at 15:05

Community

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answered Sep 08 '15 at 20:01

emcconville

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Have my vote:-) Maybe mention `mogrify` if OP has 1000+ images? – Mark Setchell Sep 08 '15 at 22:07
@emcconville, is there way to accomplish this without loosing transparent background of an png? – tukusejssirs Jun 15 '19 at 07:28
I’ve found the solution ([src](https://makandracards.com/makandra/46467-imagemagick-how-to-auto-crop-and-or-resize-an-image-into-a-box)): `convert input.png -resize 100x100^ -gravity Center -background transparent -extent 100x100 output.png` – tukusejssirs Jun 15 '19 at 07:36
Is the answer exactly as Gor asked for? I.e., Gor asked for the central part without white space on either dimension, but reading the answer over and over, I have the feeling that the answer given as of Sep 8 '15 might have filled-blanks on either dimension. Am I right, anyone? – xpt Jul 24 '20 at 20:49
It doesn't work for me in 2022. The resulting image is not cropped around the centre (and it's sad that there are so few options for the rotation centre). I managed to rotate images in Pillow (Python), it allows for an arbitrary rotation centre. – Yaroslav Nikitenko Dec 11 '22 at 15:08

score 4 · Answer 2 · answered Jan 30 '21 at 16:35

To keep the aspect ratio and don't fill anything (extent), rather crop from the longer edge which is out of aspect you could do

convert input.jpg -resize 100x100^ \
                  -gravity Center  \
                  -crop 100x100+0+0 +repage  \
        output.jpg

with option to crop more from one side if you like

Imagemagick convert resize then crop

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